The 32-year-old Zuckerberg, a White Plains native who grew up in Dobbs Ferry and attended Ardsley High School, ranks No. 5 in the world with a net worth of $56 billion.

Former New York City Mayor Michael Bloomberg, who owns an estate in North Salem, was just behind Zuckerberg, clocking in at a net worth of $47.5 billion. The former mayor's accrued wealth made him the 10th richest man on the planet, Forbes said.

Billionaire investor George Soros of Katonah checks in at No. 29 overall with a net worth of $25.2 billion.